This invention relates to the field of guidewires for advancing intraluminal devices such as stent delivery catheters, balloon dilatation catheters, atherectomy catheters and the like within body lumens.
The most common method for insertion of percutaneous catheters is the Seldinger technique. In this procedure, a local anesthesia is delivered and a skin puncture is made proximal to the femoral or brachial artery with an obturator positioned within a cannula. Once inside the artery, the obturator is removed, and the guidewire is inserted through the cannula into the artery. The guidewire is then advanced into the vasculature guided by fluoroscopic imaging to the desired site. Generally, the distal tip of the guidewire is pre-shaped or has the ability to be shaped within the vessel in order to steer the guidewire to the desired location by rotating and advancing in combination. Once the guidewire is in the desired location, a diagnostic or therapeutic catheter is advanced over the guidewire, and the desired procedure is performed.
Further details of guidewires, and devices associated therewith for various interventional procedures can be found in U.S. Pat. No. 4,748,986 (Morrison et al.); U.S. Pat. No. 4,538,622 (Samson et al.): U.S. Pat. No. 5,135,503 (Abrams); U.S. Pat. No. 5,341,818 (Abrams et al.); and U.S. Pat. No. 5,345,945 (Hodgson, et al.) which are hereby incorporated by reference in their entirety.
Because of the environment that guidewires are used in, and the purpose they serve, it is desirable to have several basic features for most, if not all, guidewires. The guidewire must navigate and advance within the lumens of a patient, coming into contact with delicate tissue. For this reason, the guidewire requires a soft, flexible distal tip which can be manipulated without causing injury to the vessel walls. Also, it must be sufficiently maneuverable to reach the required destination, which requires stable tortional characteristics, and a rigid proximal shaft that can be pushed to advance the guidewire. These characteristics are difficult to achieve, as one tends to negate the other. It is also desirable for the outer diameter of the guidewire fit properly within the inside diameter of the lumen within which it is disposed. This can be problematic for guidewires designed for the peripheral arteries, such as those found within the legs and arms, because the size of the diagnostic and therapeutic devices used in these arteries are typically large, requiring a large outer diameter guidewire, which can be stiff and inflexible due to its size. In addition, because the guidewire is steered to the desired location within the vasculature under fluoroscopy, a radiopaque marker of some type is required, which is typically a precious metal coil, band or solder. Because of the size of the peripheral guidewire, a precious metal coil can be expensive to manufacture.
Conventional guidewires for angioplasty, stent delivery, atherectomy and other vascular procedures usually comprise an elongate core member with one or more tapered sections near the distal end thereof and a flexible body member such as a helical coil or a tubular body of polymeric material disposed about the distal portion of the core member. A shapable member, which may be the distal end of the core member or a separate shapeable ribbon which is secured to the distal end of the core member extends through the flexible body and is secured to the distal end of the flexible body by soldering, brazing or welding which forms a rounded distal tip. Torquing means are provided on the proximal end of the core member to rotate, and thereby steer, the guidewire while it is being advanced through a patient's vascular system. The leading tip is highly flexible and will not damage or perforate the vessel and the portion behind the distal tip is increasingly stiff which better supports a balloon catheter or similar device.
Currently available guidewires for use in peripheral vasculature do not have a sufficiently soft and flexible distal tip with radiopaque characteristics. They have poor torque response due to helical coil members covering the entire length of the device. Also, physicians using the currently available guidewires of larger outer diameter have difficulty identifying which portion of the guidewire is adjacent the desired location within the vasculature. That is, because the distal sections of guidewires typically have a tapered core wire therein, the diameter of which in part determines the flexibility of the section, it is desirable for the physician to be able to easily determine the relative amount of support the guidewire will offer at a given location via fluoroscopic imaging.
What has been needed is a relatively large outer diameter guidewire for use in the peripheral vasculature and carotid arteries that has a high degree of torsional control, a soft and flexible distal tip with radiopaque signature, and a stable outer coil configuration. Also, it is desirable to have outer coils which are visible under fluoroscopy, but which do not require the use of precious metal components. In addition, it is desirable to have fluoroscopic markers to indicate the core wire taper transitions so that the physician may easily determine whether the diagnostic or therapeutic device is over a flexible portion or more rigid and supportive portion of the guidewire. The present invention satisfies these and other needs.